1. Field of the Invention
The subject invention relates to means for continuously conveying and orientating tie plates for use on or with track working vehicles which either renew railway track by replacing rails and either refurbishing ties or replacing ties, or on track working vehicles which construct new track in a continuous manner. In any event, there is a need for continuous delivery of tie plates from a storage or salvage area to mechanisms for laying the tie plates on the ties adjacent to both ends for each tie with the rail engaging side of the plate facing upward.
As is well known in the art, the rail seat of a conventional tie plate is canted inwardly 1/40 to 1/20 and more mass is put in the field side of the plate to compensate for the force distribution as it exists in going around curves at high speed. This imposes the additional requirement that the tie plates be delivered to the laying mechanism with the field side of the plate facing outward.
Examples of track working machinery which automatically and continuously replace old rail with new heavier rail and replace tie plates while continuously refurbishing the ties as by cribbing, adzing, creosoting, and filling old spike holes are shown in pending applications, Ser. Nos. 899,969 and 951,133 directed to high speed rail changeout machines. An example of a track renewal machine which completely replaces the ties and to which the present invention can be applied, is shown in British Pat. No. 1,339,842.
2. Description of the Prior Art
In early attempts to automate or provide equipment to work in a semi-continuous fashion, it was common to group railway cars together to perform individual tasks that previously had been performed completely by work gangs in a manual manner. An example of such a system is shown in U.S. Pat. No. 1,941,930 issued Jan. 2, 1934. While some of the functions such as adzing were performed in a semi-automatic manner by such devices, clearly the laying of new tie plates on the ties was a manual operation by distributing the tie plates from cars containing them along the right of way and then the placement of the tie plates on the ties. Even with more recent developments in track renewal, some of which embraced partial conveying of the new tie plates to a manual work station as shown in U.S. Pat. No. 3,286,648 and U.S. Pat. No. 3,747,536, the final placement and proper orientation and positioning was a manual operation.
With the advent of high speed automatic machinery as shown in the aforementioned co-pending patent applications, Ser. Nos. 899,969 and 951,133, automation of the tie plate handling became a necessity. Equipment for automatically taking up old tie plates and delivering plates back to ties in the proper position is shown in co-pending U.S. patent application, Ser. No. 951,130. An early attempt to solve the tie plate conveying and orientation problem for use with this equipment took the form of a more or less conventional cross-transfer conveying system.
With the conventional cross-transfer system, the tie plate orientation is determined at the point the tie plates are first put on a conveyor, e.g., at a storage location in an upstream gondola car. A first conveyor or series of conveyors would be power driven to convey a single line of tie plates longitudinally of the cars to the track working vehicle. The plates would be put on the conveyor system and be conveyed in a side-by-side relationship, i.e., with the tie plate ends parallel with the railway track. The cross-transfer mechanism is preferably located on the track working vehicle and is operated to push successive plates alternately outward toward the right hand rail and the left hand rail locations. Since the field side of the plate must face outwardly from the center of the railway track and the gauge side must face inwardly, the plates are placed on the first conveyor with the ends of adjacent plates pointing in opposite directions. The cross-transfer mechanism will thus transfer the tie plates from a single row, first longitudinal driven conveyor to two single row, second longitudinal conveyors which will be generally in line with and feed the right hand and left hand mechanisms for positioning and laying the tie plates adjacent each end of each tie for reception of new rails.
The foregoing conventional cross-transfer conveying system has many limitations, particularly as applied to a high speed track renewal or construction machine, such as the rail changeout machines set forth in the aforementioned pending patent applications. This machine can automatically and continuously replace old rail with new, heavier rail, replace tie plates and continuously refurbish the ties as by cribbing, adzing, creosoting and filling old spike holes. Moreover, this machine can operate at speeds of 2400 ft./hr. which virtually exceeds the rate at which a cross-transfer conveying system can operate. At this speed, close to 3,000 tie plates must be delivered per hour which virtually exceeds the capacity of a single row longitudinal conveyor. The difficulty of synchronizing the initial loading of the tie plates also becomes more complex as speed is increased. This can be illustrated by the problem of employing four laborers in a gondola car to load the conveyor. Since the plates must be staggered as aforementioned, the four men must simultaneously drop the plates on the conveyor in less than five seconds, and with a 25 lb. plate, each man must handle approximately 150,000 lbs. per 8 hour shift.